JPH0560144B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to the display of graphical information. In particular, the present invention relates to the generation and manipulation of images and data on display systems.

[Prior art]

It is quite common in the computer industry to display and communicate information to users through graphical displays. These representations can take a variety of forms, such as, for example, alphanumeric characters, graphs of parallel or other coordinates, as well as the shape of well-known physical objects. Historically, humans have interfaced with computers through a system of individual commands, typically consisting of a combination of both textual and mathematical symbol characters. There are many such systems, including the Fortran, Algol, PL/1, Basic, and Kobol programming languages that convert a set of user commands into machine-executable "object" code.

However, a user's proficiency in programming or interacting with a computer-based system depends on the approximation of that system to the user's own logical thinking. If users could enter commands in the order that makes the most sense to them, rather than having to translate the desired commands into programming language code,
Great user efficiency is achieved in using the system.

One system that has been developed to minimize the learning period for users to become proficient at interacting with computer systems is what is often referred to as an "object-oriented" or "small talk" system. This small talk method replaces many commonly coded programming commands with two-dimensional graphics and animations on the computer display. Because humans can think more easily with images, they can absorb and manipulate information presented through vision more quickly than through text. The particular type of graphical interface that a user uses to interact with a machine can vary depending on the application.

One common small talk interface method uses a combination of text and graphics to convey information, and uses a cathode ray tube (CRT)
A number of "windows" are displayed at the top. For example, each window can be made up of overlapping file folders, similar to those used in a normal file cabinet, and can contain information about the current work file. folders are fully visible up to their tops. Users can add or delete information from the files, refile the file folders to another location, and use the actual files in the office. You can manipulate files as if you were
Machine operation is made easier for the user by graphically displaying images that represent the objects of the user's commands, and by allowing the user to manipulate the images as if they actually constituted the objects. , a stronger man-machine interface is achieved. For example, D. Robson's ``Object Oriented Software Systems'' (Object Oriented Software Systems)
-Oriented Software Systems), BYTE magazine, August 1981, P74, vol.6, No8;
and “The Small Talk Environment” by L.Tesler.
Smalltalk Environment), BYTE,
See August 1981, P90, vol.6, No.8.

Although a variety of graphical displays are desired in small talk or other systems, large amounts of memory have traditionally been required to generate, store, and manipulate graphical characters. In its simplest form, a block of memory can be allocated in the data processing storage system that maps each memory bit (1 or 0) to a corresponding picture element (pixel) on the display system. Thus, filled with data in the form of images and/or text
The entire screen of a CRT is represented as a 1 (black dot) or a 0 (white dot) in a memory block known as a "bitmap." However, a one-to-one correspondence between a bitmap and a CRT display requires a significant amount of storage space in the computer's core memory. Furthermore, the generation and manipulation of images or characters requires that virtually every bit in the bitmap be updated after any modification to the image or the like.
This procedure is repetitive and time consuming, and significantly interferes with the practical use of interactive graphic display systems.

One way to provide the necessary graphical capacity for a system like SmallTalk is through the Xerox Learning Research Group Palo Alto Research Center (Xerox Learning Research Group Palo Alto Research Center).
Learning Research Group Palo Alto
``Bit Blt'' (Bit Boundary Block Transfer), as developed by the Research Center), Palo Alto, California. The Swalltalk by D. Ingalls
Graphics Kernal), BYTE, P168,
See August 1981, vol.6 No.8. BitBlt is itself a small bitmap and utilizes regions that define simple shapes, such as arrowhead shapes to be used as cursors, patterns, etc.
As discussed below, BitBlt transfers characters from a source bitmap, such as a font file of characters, to a destination bitmap (i.e., a memory block of content to be displayed on a CRT) at predetermined coordinates. By using a "clipping rectangle" to limit the valid area of the destination bitmap, only the portion of the scene to be transferred that falls within the window can be transferred, allowing portions of a larger scene to be mapped within the window. Additionally, various transfer operations are provided to control the combination of the current scene previously stored in the destination bitmap and the scene or character being transferred. however,
The BitBlt system has limitations on the formats of images that can be transferred and manipulated. In particular, BitBlt is limited to transferring rectangular areas. Because of this limitation,
BitBlt cannot transfer data to superimposed windows, etc., so its use is limited to graphics tools. Furthermore, a large amount of memory is required for the BitBlt system. Other limitations in prior art systems such as BitBlt are discussed later to make the nature of the invention more clear.

[Summary of the invention]

The present invention provides a means by which arbitrarily shaped regions can be defined and stored using significantly less memory than was possible in the prior art. moreover,
The present invention provides a means by which a digital computer can efficiently and quickly perform operations corresponding to a domain.

The present invention provides improved graphics capabilities. This makes it possible to display and operate an area (input area) arbitrarily limited by the "reversal point." An inversion point is a point at which the states of all points with coordinates to the right and below are inverted (eg, a binary zero is converted to a binary 1 and vice versa). A "region" is defined as any area that may include multiple separate areas. In this way, any arbitrary shape, such as an "L" shape, can be simply treated as a predetermined area to be manipulated. By defining a set of inversion points for a given region, it is not necessary to store all the points that make up the region in memory, but only the inversion points that define the region.

Briefly, according to an embodiment of the invention, means are provided for inputting the input area to be displayed. The input region can consist of any shape or area, and its perimeter need not be a continuous curve, and therefore can include discrete areas. The information in this input area is digital
coupled to a computer. The computer determines the locations of the flip points needed to define the input region and places the flip points within the region in the order or convention from left to right and top to bottom based on their coordinates. Sort accordingly. According to an algorithm, the information of the region (or parts thereof) is transferred into computer memory, where it is manipulated so that the composite region is displayed as a contrast-forming area on a suitable device, e.g. a cathode ray tube (CRT). .

A scanline mask consists of a single scanline buffer that is stored in the destination bitmap (video memory) and represents in binary form the current region being displayed. The destination bitmap consists of blocks of memory containing bits, each bit corresponding to a pixel on the display device. The scan line mask is scanned sequentially downward to "slice" the current area in horizontal rows corresponding to each raster on the CRT display. Similarly, data (in the form of characters, etc.) from a source bitmap or font file that is to be added to a portion of the destination bitmap is sliced into horizontal scan line buffers corresponding to each raster on the CRT. be placed.
When a horizontal scan line is transferred from a source bitmap, etc. to a destination bitmap, the contents of the source scan line buffer are compared with the contents of the scan line mask, and the source scan line buffer is changed by masking the source scan line. Ensures that only the selected portion is transferred to the destination bitmap. By using various region operators, priorities can be established between current regions and new regions. In this way, patterns (e.g. striped, checkered, etc.) can be added to the current region, text can be overlaid, scrolling of the text within the region can be easily accomplished, and a number of graphical operations can be accomplished. can do.

The resulting target bitmap is converted into a signal applied to a CRT or other display device,
This image is then displayed in the usual way.

〔Example〕

Notation and Terminology The discussion above uses many algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are used to effectively communicate data processing techniques to other data processing engineers. It is a means.

An algorithm here is generally a coherent sequence of steps to obtain a desired result. These steps are those requiring physical manipulations of physical quantities. Typically, these physical quantities are stored, transferred,
are electrical or magnetic signals that can be combined, compared, and otherwise processed. It is common usage, and at times, convenient to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. but,
These terms should be associated with the appropriate physical quantities and should be kept in mind as convenient labels applied to the physical quantities in question.

Furthermore, the operations performed are terminology that describes the mental activity of the human operator, such as addition or comparison. Such human capabilities are neither necessary nor desirable for the operations forming part of the present invention. This operation is a machine operation. Machines useful for carrying out the operations of the present invention include general purpose digital computers or other similar devices. In all cases, one should keep in mind the distinction between the method of operation of the computer and the method of computation itself. The present invention relates to method steps for operating a computer in processing electrical or other physical signals (eg, mechanical, chemical signals) for the generation of desired physical signals.

The invention also relates to an apparatus for performing these operations. The apparatus may be specifically configured for a specific application, or may consist of a general-purpose computer that is selectively activated and configured by a computer program stored within the computer. The algorithms presented herein are not specific to any particular computer or other device. In particular, various general purpose machines may be used with programs written in accordance with the following teachings, or specialized equipment may be more convenient to perform the necessary method steps. . The required structure for a variety of these machines will appear from the description below.

The following explanation can be divided into several parts. first,
Handles the overall system arrangement for generating computer graphics. Subsequently, sorting of specific inversion points of the input area by inversion points, operations (logical operations) on inversion points, generation of scan line masks, and area transfer operations are handled.

In the description, reference is made to certain details such as algorithm conventions, number of bits, etc. in order to provide a more complete understanding of the invention; however, it will be apparent to those skilled in the art that the invention may be practiced without such details. Will. On the other hand, regarding well-known circuits and configurations,
The detailed explanation has been omitted to avoid unnecessary redundancy.

General System Configuration FIG. 1 shows a typical computer display device for generating computer graphic images in accordance with the present invention. computer 20
consists of three elements. The first is input/output (I/O) circuitry 22, which is used to communicate information to and from other parts of computer 20 in a suitable manner. Central processing unit (CPU) 24
and memory 26 are shown as part of computer 20. The CPU 24 and the memory 26 are
It is commonly found in general purpose computers and most special purpose computers. Computer 20 is shown to be an extensive data processor due to the several elements it contains. Computer 20 is a machine manufactured by Apple Computer, Inc. (California, USA), although other computers of similar capabilities are readily suitable to perform the functions described below.

A keyboard is shown as input device 30 in FIG. The input device may be a card reader, magnetic or paper tape reader, or other well known input device (including, of course, other computers). The mass memory device 32 is connected to the I/O circuit 22.
is coupled to add storage capacity to computer 20. Mass memory device 32 may contain other programs, fonts of predetermined characters, etc., and may take the form of a magnetic or paper tape reader or other well-known form. The data held in mass memory 32 is captured within computer 20 as part of memory 26.

A display monitor 34 is shown displaying images. The display monitor can be a CRT display or a variation thereof. Cursor control (mouse) 36 is used to select command modes and edit graphics data, such as special images, and provides a more convenient means for entering information into the system.

FIG. 2 shows a typical arrangement of the main program within memory 26 shown in FIG. In the preferred embodiment, the (video) destination bitmap 38 comprises 32 kilobytes of storage.
It is shown. This purpose bit map 38 is
Represents video memory for video monitor 34. Each bit in the destination bitmap 38 corresponds to the coordinates of a corresponding pixel on the display monitor (more precisely, the coordinates of the top left corner of the area occupied by the pixel). Therefore, the target bitmap 38 can be described by a two-dimensional array of points with known coordinates. If other display means are used, such as a printer, the contents of destination bitmap 38 will represent the data points displayed by that display means. Memory 26 also includes a program 40 that represents a diverse series of instructions for execution by the CPU. For example, limit programs, monitor and control programs, disk operating programs, etc. that perform the operations and routines described herein.
The system, etc. can be stored in memory 26.

The source bitmap 42, including regions, fonts, data structures, coordinates, and characters, may be stored in memory 26 or may be temporarily stored in mass memory 32 if required by the application. Space is left within memory 26, as indicated at 44, for other programs and spare memory. Other programs may include calculation and utility programs that may be needed.

Indication of Reversal Point in a Determined Area In the present invention, an arbitrarily determined area is represented by a "reversal point." The present invention defines any area (which can include a plurality of discrete areas of any shape or configuration) as a "region."
In FIG. 3a, a reversal point 40 is illustrated. An inversion point is a point where the states of all points with coordinates to the right and below are inverted. Therefore, as shown, all areas to the right and below point 40
If 0 is initially set on a white background, then it is black forming the contrast. In order to physically represent the reversal point, the position of the reversal point can be written in a bitmap of memory by its coordinates.

As shown in Figure 3b, the two reversal points 4
0,42 in a bitmap such as the target bitmap 38 and then displayed on the monitor 34,
A vertically unbounded black strip results.
Adding point 42 to the bitmap inverts the state of all points with coordinates to its right and below, negating the effect of point 40, thereby defining a vertical black strip.

Similarly, four reversal points 40, 42, 44, 46
defines a square or quadrilateral as shown in Figure 3c. Other areas can also be defined using inversion points, and blanks can also be easily generated within a predetermined shape. Furthermore, since all shapes within the region are defined by the coordinates of the inversion points, it will be clear that a given region can encompass any number of discrete areas.

Additionally, circular and other non-linear regions can be defined by appropriate positioning of the reversal points. Referring to FIG. 3g, the diagonal line 43 is "X" and "Y"
can be defined between points "X" and "Y" by a series of steps of two reversal points between them. Although a direct diagonal line between points would be preferred, the physical configuration of the raster display monitor 34 precludes this. Since each pixel on a CRT display occupies a unit area between coordinates, a particular pixel is accessed by the coordinates of the grid point above and to the left of it. Thus, to approximate the diagonal, a step-like function of reversal points is required that defines a series of horizontal line segments.

Once a given region is defined by the inversion points as an input region, typically only the inversion points are kept in memory 26, unlike many prior art techniques which require storing all the points that make up the image. There is only a need. In the example, the area is the cursor
Inputs are entered into 20 by the user via controls 36 or other input means and stored in memory as information in the form of bitmaps. The position of the inversion point defining the region is determined by detecting the starting point of a horizontal line segment that forms part of the boundary of the input region. Referring to FIG. 3h, line segments 80, 85, 90, 10
0,125 is shown. The inversion points are determined by the coordinates corresponding to the starting point of each line segment, and the entire area is determined by these inversion points. Vertical line segments within the region are automatically generated using the reversal points described above, so they are ignored. The computational steps to be performed by computer 20 for horizontal line segment detection and separation are believed to be obvious to those skilled in the data processing arts and will not be described here; The points, according to their coordinates,
Arranged by sorting according to a left-to-right, top-to-bottom order (convention), the coordinates of the inversion points are arranged in a list so that they can be read from memory in the order in which the pixels are scanned. For example, referring to the region of FIG. 3e, the ordered list of inversion points according to this convention is: 54, 56,
58, 60, 62, 64, 66, 68, 70, 72, 74, 76.

The method described above allows simple operation for areas such as those shown in FIGS. 4a-e.
Typical operations according to the invention on an ordered list of inversion points include intersecting regions, merging,
Together with the difference and exclusive OR, it is a function of point membership determination.

Often during graphics operation, it is possible to determine whether a point within the target bitmap 38 (and thereby displayed on the display monitor) lies within a particular region. This feature is commonly referred to as "point membership." Determining point membership has traditionally required extensive data manipulation and calculations. For example, one conventional technique for determining point membership was to calculate and sum the angles from the point in question to the region of interest. If the sum of the angles is equal to 360°, then
Point membership exists within the region.
This conventional method of determining point membership requires numerous iterative calculations and is very time consuming.

However, the reversal point of the present invention is the point
Provide an effective means of determining membership. Referring to FIG. 4a, the present invention scans from top to bottom an already arranged list of inversion points defining the region of interest. Set a variable (its initial value is false (“0”), for example) in memory,
If the reversal point has a vertical coordinate greater than or equal to the vertical coordinate of the point in question (point "P" in Figure 4a), and the horizontal coordinate of the reversal point is that of point "P", If it is smaller than that, the variable is toggled (if the initial value is false, it is changed to true (“1”)).

In this way, each time the reversal points above and to the left of the point in question are detected, the above variables are toggled (changed). Then, after scanning the list of inversion points defining this region, if the variable is true (i.e., if an odd number of state changes have occurred), then
The point in question (ie, point "P") lies within a particular region. However, if the variable is false (ie, the state change does not occur or occurs an even number of times), then the point of interest is not within the domain. Thus, a fast and efficient method of determining point membership using reversal points is not available in the prior art and is proposed by the present invention.

Area to Scan Line Buffer Conversion The use of an ordered list of inversion points provides a simple means of representing the contents of each raster scan line of monitor 34. In FIG. 5, a portion of memory 40 (see FIG. 2) is allocated as a plurality of single scan line buffers. In a preferred embodiment, the single scan line buffer is made large enough so that each pixel in each horizontal row on a CRT monitor screen or other output device is represented by one bit in the buffer. The region previously defined by the ordered list of inversion points can be represented by the state of the bits in a single scan line buffer. For each horizontal line displayed on the monitor 34 (indicated by V ₀ , V ₁ , V ₂ ...V _o+1 in Fig. 5), the vertical coordinate of the corresponding scanning line (horizontal line) is determined. An inversion point with a change in bit state at the corresponding coordinate of a single scanline buffer (i.e., a ``1'' if the field of the scanline is initially ``0'')
It is represented by. All bits between a pair of inversion points in scan line 155 are inverted to produce a true representation of the area to be displayed from the ordered list of inversion points. In this way, any area is "sliced" horizontally and sequentially into segments the width of a single scan line by scanning each horizontal row to be displayed, as shown in FIG. Ru.

As will be discussed below, the use of a single scan line buffer transfers regions from the source bitmap 42 to the destination bitmap 38 and properly "masks" them.
Any area can be transferred and manipulated, unlike prior art systems such as BitBlt which are limited to transferring rectangular areas.

Furthermore, it will be appreciated that the conversion from area to scan line buffer is reversible. If the region is represented in the form of a single-scanline buffer, then an ordered set of inversion points is defined above (V ₁ ) in the buffer.
Once the area has been scanned from down to (V _o+1 ), it can be identified again by looking for an inversion state on the buffer. The position of the reversal point on the buffer is
The location of the reversal point is easy to locate since it is the point at which a bit state change is detected (ie, a ``1'' when the next bit is a ``0''). In an embodiment, the location of the inversion point is the current scan line (e.g.
V ₃ ) buffer contents and previous scan line (e.g. V ₂ )
can be easily determined by an exclusive OR operation between the buffer contents of . In this way, the portion of the area that does not change between scan lines at successive vertical positions is ignored since there is no inversion point if the content is the same between a scan line at one vertical position and the next scan line. be done. Furthermore, the horizontal position of the inversion point can be determined by shifting the scan line obtained by exclusive ORing one bit to the right and performing an exclusive OR operation. For example, if the scan line buffer V _N and
After an exclusive OR operation between V _o-1 k, assuming that the result is 01110011, by shifting the result one bit to the right and performing another exclusive OR operation, we get the following: Get results.

01110011 00111001(1) 01001010 Reversal Point Location for Scanline V _N The commands to be executed by computer 20 to determine where a change of state exists in a single scanline buffer will be apparent to those skilled in the art. Since it is possible, further explanation will be omitted.

Region Operator By using a single scan line buffer to systematically represent the contents of a region, the operations such as join, intersect, etc. described above are easily accomplished. For example, the intersection operation shown in FIG. 4b provides an inverted point representation of the hatched area and is obtained by "ANDing" two overlapping regions "A" and "B". Referring to FIG. 6, a single scan line buffer is defined for each of regions "A" and "B". For each horizontal raster row of a CRT display, a separate single scan line buffer represents the contents of each area in binary form. The contents of the single scan line buffer are then subjected to operations to achieve the desired function. In the case of FIG. 4b, "AND" is performed to produce a composite scan line. For example, if for vertical position _V1 , "A" scan line = 11111100 "B" scan line = 10010001, then the resultant scan line after the "AND" operation would be 10010000. moreover,
The same "AND" operation is done for each horizontal row V _o achieving each region. The result of the above operation is a composite display of the cross-hatched region "C" of FIG. 4b, one scan line at a time. The locations of the inversion points that make up the shaded region "C" can be derived using known techniques such as the exclusive OR operation described above.

Similarly, an "OR" operation between two regions is utilized to accomplish the combination function of FIG. 4c. To obtain the “difference” in Figure 4d, the operation between the two regions is (NOT “S”)
AND “R” and the states of all binary quantities represented in the “S” scanline buffer are inverted before “ANDing” their contents with the “R” scanline buffer. .

Finally, the exclusive OR operation in Figure 4e simply performs an exclusive OR on the contents of each region's scanline buffer, similar to what was done in the example above for the "AND" operation. It is achieved by doing so. However, it will be apparent to those skilled in the art that the use of an ordered list of inversion points simplifies exclusive OR operations. This operation is performed by merging and sorting the lists of inversion points in regions "T" and "U" of Figure 4e, and by discarding points with the same coordinates in both regions. can be achieved. In other words, computer 20
simply treats the ordered list of inversion points defining the regions "T" and "U" as one big list, and sorts all the inversion points from left to right and from top to bottom according to the above convention. Sort by. The obtained list of reversal points represents regions that include reversal points in either region "T" or "U", but not in both.

It will be appreciated that numerous other operations and combinations of operations using the inversion points of the present invention and the use of scan line buffers can be performed in arbitrary areas compared to the prior art. .

Scan Line Mask Referring to FIG. 7, the use of a scan line mask to clip arbitrary areas is symbolically illustrated. The previously defined area 160, which has been converted into an ordered list of inversion points, is used to compare all added images to be displayed on the monitor 34 before affecting the destination bitmap 38. used as a “mask”. As shown in FIG. 9, it is often desired to overlap a large number of regions with a predetermined priority.
In FIG. 9, folders are shown superimposed, and in accordance with the present invention, text can be displayed on each displayed folder, as well as any other area. As mentioned above, conventional techniques such as BitBlt are limited to clipping rectangular areas. Thus, the versatility of the system was severely limited in the prior art by the constraint of operating only in a rectangular area and by the inability to operate in areas other than the topmost window (e.g., folder 210). .

As symbolically illustrated in Figure 7,
Other regions, such as patterns or characters, are compared one scan line at a time to a bitmap "mask" of existing regions currently being displayed. As described below, by defining region operators, the priorities of various masks can be determined. Thus, patterns can be formed with fonts and other characters within any area. "Region clipping" is performed according to a region operator such that overlapping region portions are selectively displayed.

Referring to FIG. 8, each source bitmap 42, which can be composed of images, characters, fonts, etc. to be displayed, is sliced, for example, as described above in the section "Conversion from Area to Scan Line Buffer". and converted to a single scan line buffer. In this manner, all areas to be displayed are represented in binary by scanning the source bitmap 42 horizontally and developing the inversion point coordinates along the buffer.

The currently displayed area becomes a bitmap "mask" area against which the new area you wish to display will be compared. As with any new source area to be added, the currently displayed area is converted to a single scan line buffer representing the contents of the destination area in binary form. Depending on the particular conversion mode operation, each scan line of the new region is selectively transferred to the destination bitmap 38 and displayed on the display monitor 24.

The transfer mode operator used is a function of the desired output. The area operators are OR,
It includes the functions of AND, exclusive OR, NOT, and their combinations. For example, if the current scan line mask buffer for row V ₁ on the CRT is
01101010 and the current source scan line buffer for V ₁ contains 01100110, it will be displayed on monitor 34. The result after the “AND” operation is as follows.

01101010...Contents of the scan line mask buffer (AND) 01100010...Contents of the source scan line buffer 01100010...Contents of the target bitmap scan line to be displayed In this way, some, but not all, of the new source area will be displayed on the display device. transferred and "clipped" depending on the particular transfer operator selected. Furthermore, it will be appreciated that the shape of the area of operation is irrelevant to the method of the invention. The use of inversion points and single scan line buffers defines, masks, and transfers arbitrary regions.

In the preferred embodiment, three separate scanline mask buffers are provided for comparing new source regions. The "user area" mask consists of the current area in the display that would be affected by the new area if it were transferred. The "visible area" mask is defined as the visible portion of the current area (folder 200 in FIG. 9) that is currently displayed. The "clipping region" consists of the visible portion of the user region that clips the new source region so that only a portion of the new source region is transferred. In this manner, the new source area to be transferred from source bitmap 42 to destination bitmap 38 is passed through the equivalent of three scan line mask buffers. In practice, each scanline mask's buffer contents are ANDed together and the resulting composite scanline mask is used to mask the new area.

FIG. 9 shows an example of the output displayed on monitor 34 in accordance with the present invention. Region 200 was initially defined by the user and stored in memory 26 as an ordered list of inversion points. As mentioned above, by defining appropriate region operators, region 200 can be transformed into region 21.
Area 2 so that it is located between 0 and 240
10 and 240 are displayed. Similarly, text is formed within the area of each folder shape, and with appropriate area clipping using a scan line mask as described above, for each area only that part that would be visible using the actual folder is displayed. be done.

Additionally, although the present invention has been described with emphasis on binary presentation (black and white) on display device 34, it will be apparent to those skilled in the art that appropriate inversion point and scan line masking for color images may be provided. Will. For example, to generate the colors red, green, and blue, one for each color.
Three inversion point area representations are available. Thus, the presence of an inversion point in one color region can cause a color gun, such as in a color CRT, to be selectively discharged for that color. Similarly, various colors can be achieved by appropriate combinations of the three inversion point representations of each region stored in memory.

Coding Details No specific programming language was provided for implementing the various procedures described above. This is probably due to the fact that not all available languages can be mentioned. Users of a particular computer will find the language most suitable for their purposes. Indeed, it is useful to implement the invention in assembly language that provides machine-executable object code.

Because the computer and monitor system that can be used to implement the present invention is comprised of many different components, a detailed program listing has not been provided. The above description will be sufficient to enable one skilled in the art to practice the invention. Techniques have been disclosed that can be advantageously used in digital computers to provide improved graphics capabilities. The use of inversion points and scan line buffers defines arbitrary regions faster and more efficiently than conventional systems in the art.
can be manipulated and transferred.

Although the invention has been described with reference to certain computer systems with reference to FIGS. 1-9, these figures are illustrative only and are not intended to limit the invention. Furthermore, it is apparent that the present invention has utility in applications where graphical displays on CRTs or other display devices are desired. Many changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a computer adopting the present invention, FIG. 2 is a diagram showing an example of a memory configuration in the computer of FIG. FIG. 5 is a diagram illustrating an operation on a region using inversion points according to the present invention. FIG. Figure 6 is a diagram to explain an "AND" operation between two areas, one scan line at a time, Figure 7 is a portion of the source area to be displayed. A diagram to explain the operation of bitmap mask for selectively masking the
FIG. 8 is a conceptual diagram illustrating the use of a single scan line buffer and an operational line mask to selectively mask portions of the source area prior to transfer to the destination bitmap for display; FIG. Figure 3 illustrates the results of the present invention using an inversion point scanline mask system. 20... Computer, 22... Input/output (I/O) circuit, 24... Central processing unit, 2
6...Memory, 30...Keyboard, 32...Mass memory device, 34...Display monitor,
36...Cursor control.

Claims (1)

Claims: 1. A computer display device including a memory, comprising a plurality of pixels for providing a display, the display state of each pixel being selectively controlled to produce a contrast-forming area. A method for generating a scan direction extending in a direction scanned on a display means and forming part of a boundary of said region by examining input information in the form of a bitmap defining an area to be displayed by a contrast-forming area. the starting points of the line segments are searched as reversal points, the coordinates of these reversal points are stored in a memory, and the coordinates of the reversal points are read out from the memory in the order in which the pixels are scanned by the display means. sorting the coordinates of the reversal points stored in to generate an arranged list of reversal points, and according to the arranged list of the reversal points, the line segment in the scanning direction starting from the reversal point, and , a computer display characterized in that a boundary of the area is formed by an orthogonal line segment that is orthogonal to the line segment in the scanning direction and has the reversal point as a starting point, thereby generating a figure on the display means. How to generate figures in the device. 2. A method for generating figures on a display means, in a computer display device including a memory, comprising a plurality of pixels to provide a display, the display state of each pixel being selectively controlled to generate a contrast forming area; examining input information in the form of a bitmap defining the area to be displayed by the contrast-forming area and determining the origin of a line segment in the scanning direction extending in the direction of scanning on the display means and forming part of the boundary of said area; , as inversion points, and storing the coordinates of those inversion points in a memory, such that the coordinates of the inversion points can be read from the memory in the order in which the pixels are scanned by the display means. sorting the coordinates of to produce an ordered list of reversal points, and for at least two ordered lists of reversal points delimiting each of the at least two said regions, AND, OR,
A logical operation including at least one of NOT and exclusive OR is performed, and depending on the result obtained from this logical operation, the line segment in the scanning direction starting from the reversal point, and
forming a boundary of the area by an orthogonal line segment that is perpendicular to the line segment in the scanning direction and has the reversal point as a starting point;
A method for generating graphics in a computer display device, characterized in that the graphics are generated on the display means.